Iowa’s reputation as a right-wing outpost, untouchable by mainstream presidential candidates, is a legend that needs an injection of facts.

Mitt Romney’s candidacy, more than any other, stirs Iowa Republicans’ anxieties about the caucus state’s role in the presidential nominating process. The notion that the national frontrunner can’t or may not win the first significant candidate test is, for some, like a hair in the back of the throat.

The “can’t” part of the equation might indeed be a problem for the caucus process if it were true. But history shows it’s not. The eventual GOP nominee has won two of the past five contested caucuses since 1980. During this period, four of the five caucus winners has been named either Bush or Dole.

In fact, it’s not far-right outsiders but establishment-favored “brand-name” Republicans who have snared the most caucus votes over the years. Mike Huckabee’s victory in 2008 was the exception. That was also the first year the eventual GOP nominee didn’t snag one of the fabled three tickets out of Iowa. John McCain tied for third, statistically, but finished 0.4 percentage points behind Fred Thompson.

Sorting candidates by type

John Stineman, a Republican policy consultant, has watched the characterization of Iowa as a conservative-only contest with dismay. He decided to test his theory that Iowa, historically, has been far more open than the pundits suggest.

He concluded that there are three tickets out of Iowa — three different types of tickets. Download the graphic.

“You group candidates together, they start to look a little different,” he said.

Using market-research techniques, he bunched candidates into loose categories and looked at each group’s performance in the caucuses:

Brand-name Republicans: These candidates were well-known, had either run before or were seen as “establishment” candidates. Most would be at home on anybody’s short list of presidential contenders even outside the campaign season. For example, Romney and McCain were tagged as “brand-name Republicans” in 2008. George W. Bush was alone as the standard-bearing contender in 2000, and Bob Dole held that role in 1996.

More conservative/outsider: This group includes the social-religious conservative class of candidate, such as Huckabee in 2008; Alan Keyes and Gary Bauer in 2000; Keyes and Pat Buchanan in 1996 and Pat Robertson in 1988. It also takes in libertarians like Ron Paul.

Idea or leadership Republicans: Stineman describes this harder-to-define category as candidates who center their campaigns on new ideas or approaches, like Forbes’ flat tax, or Jack Kemp’s blurring of party lines on certain social issues. The group also includes candidates who were recognized as strong leaders but hadn’t achieved brand-name status, such as former New York Mayor Rudy Giuliani or former Tennessee Sen. Fred Thompson.

Since 1980, brand-name Republicans have won the caucuses every year except 2008, which was Huckabee’s year. On average, this type of candidate has won 43 percent of the vote over the past five contested caucuses.

A more conservative/outsider candidate placed second in three out of the five races from 1980 on, and first in 2008. These candidates more often get their status from beating media expectations in Iowa, rather than actually winning on caucus night. The average share of the vote from 1980 on was about 32 percent.

Idea candidates/leaders had their best result with Forbes’ second-place finish in 2000. Otherwise, they have finished third or worse and have averaged 23 percent of the vote since 1980. This type of candidate has never won the nomination, Stineman notes, a bit ruefully. “As somebody who’s worked for two of them in the past, I wish they would,” he said.

Stineman isn’t working for any candidate this cycle. His clients are involved in issue advocacy, though, which means he has an interest in seeing the caucuses continue to thrive.

Candidate sorting is subjective

There’s plenty of room for debate about how to sort the candidates. Some Iowa Republicans tell me they dislike labels generally, because they are almost always inadequate. Stineman says his purpose wasn’t to label but rather to classify candidates as a way to spot historical trends.

Some candidates may jump from one bucket to another, even during the course of a campaign. For example, Romney might have started the 2008 race as more of an idea/leadership candidate, despite his well-known family name. But he quickly earned the brand-name status through his establishment favor and fundraising prowess.

There are some quirks in the trend lines. Candidates who have run before tend to improve their standing. In 2012, repeat candidates Romney and Ron Paul could continue the trend of improving their 2008 finishes.

Brand-name candidates also draw support from voters across the political spectrum, Stineman noted. George W. Bush was a rock star, who drove out other mainstream contenders. Ronald Reagan, the only conservative/outsider to win the nomination, would certainly be considered the definition of a brand-name Republican today. But Stineman said he pegged him as an outsider because the establishment didn’t embrace Reagan at the time.

What’s does this mean for 2012?

The 2012 field may not be set, and Stineman says some candidates have yet to define themselves.

Huntsman, the former U.S. ambassador to China, might position himself as a mainstream alternative to Romney, or he could focus more heavily on his foreign-policy background as an idea candidate. Texas Gov. Rick Perry, if he decides to run, might qualify as a brand-name Republican, unless he pushes his outsider status. Tim Pawlenty has tried to appeal across the board, and he could become the establishment pick in Iowa.

The number of conservative/outsider candidates already in the race — with the potential addition of Sarah Palin — suggests no one candidate is likely to match Huckabee’s 34 percent finish. But a lot depends on how many of these candidates survive the Iowa GOP’s straw poll in August.

The fact that neither Romney nor Huntsman are planning to participate in the straw poll could give Pawlenty an uncontested shot at voters who lean toward brand-name candidates.

The 2012 caucus participant may not look exactly like the 2008 model. Independents and moderates who attended Democratic caucuses last time may join the GOP ranks next year.

Des Moines Register pollster J. Ann Selzer pointed out in a Politico essay last week that the ranks of 2010 GOP primary voters are ripe for candidates to pluck new caucus participants.

We can get too caught up in looking at caucus history. Stineman’s theory is just one of probably dozens of ways caucus results have been sliced and diced over the years. But I’m sharing it here because it’s an instructive reminder that caucus results look very different outside the prism of media expectations and punditry.

Romney and Huntsman are making their own calculations about best way to the nomination. One truism about Iowa caucuses has held up through the years, however. The caucuses are like lottery tickets: You can’t win if you don’t play.